What actually drives the cost of a terrace
Published on 4 August 2026
You ask three contractors to quote for a 30 m² terrace. The first gives you a figure, the second gives you double. Both are reputable firms. How?
Because a terrace is almost never just “a terrace”. The cost is in what sits underneath the slabs, and around them.
What carries the most weight
The ground
The least predictable item. Firm, level ground needs little preparation. Clay, a slope, or recently filled ground means digging deeper, a thicker sub-base, sometimes drainage. None of that is visible once it’s finished — and it’s often a third of the bill.
Where the water goes
A terrace has to fall away from the house, roughly 1.5%. If the water has nowhere to go, that somewhere has to be built: a channel, a soakaway, a connection. Skipping this is the single most common reason terraces cause trouble two winters later.
Getting to the site
A terrace behind a terraced house with no machine access means everything — spoil out, gravel in, slabs in — goes by wheelbarrow. That can be several extra days of labour.
The material
The visible choice, and the one people think of first. Concrete slabs, natural stone, timber, composite: the price difference is real, but it’s rarely the largest item.
What to ask every contractor
Quotes only become comparable when they describe the same things. Always ask:
- How deep is the excavation, and what exactly is the build-up?
- Where does the water go, and by what means?
- Is removing the spoil included?
- How are the edges finished: kerbs, steps, the junction with the wall?
- What happens if the ground turns out worse than expected?
If one quote is a single line and another is a full page, they are not offering the same work.
What about permission?
A terrace at ground level usually needs no building permit. As soon as it is raised, involves a structure, or affects a boundary, the commune may have a say — and the rules differ from one Luxembourg commune to the next. Check before the materials are ordered, not after.
Have a project and want a quote that breaks these items out? Tell us about it — we reply within 24 hours.